SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a25f8bf7e2ce221efa40538bafbac9402b928a03572c362df6be6881ddb6b1c2' 
  AND token = 'kmZ7E16BIshbfJhMHaaOaBexJYsveEoOBi+LCtr20jI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}